Notwithstanding the restrictions which may otherwise be provided by law with respect to the investment of funds, all administrators, custodians or trustees of pension funds other than the board, each political subdivision of this state and each county board of education may invest funds in the securities of or any other interest in any investment company or investment trust registered under the Investment Company Act of 1940, 15 U.S.C. § 80a, the portfolio of which is limited: (i) To obligations issued by or guaranteed as to the payment of both principal and interest by the United States of America or its agencies or instrumentalities; and (ii) to repurchase agreements fully collateralized by obligations of the United States government or its agencies or instrumentalities: Provided, That the investment company or investment trust takes delivery of the collateral either directly or through an authorized custodian: Provided, however, That the investment company or investment trust is rated within one of the top two rating categories of any nationally recognized rating service such as Moody's or Standard & Poor's.